1. Field of the Invention
The present invention relates to a reading unit and an image reading apparatus.
2. Description of the Related Art
A conventional reading unit which includes a carriage extending in a first direction and an image sensor has been known. The image sensor has a case extending in the first direction and a plurality of light receiving elements contained in the case and aligned in the first direction. The carriage supports the image sensor thereby constituting the reading unit.
In more detail, the carriage has a reference surface facing the bottom surface of the image sensor in a state that the image sensor is supported by the carriage, a pair of supporting portions provided respectively on both sides in the first direction, and one end edge positioned on one side of the reference surface in a second direction orthogonal to the first direction and parallel to the reference surface. The case has a pair of supported portions provided at positions corresponding to the pair of supporting portions. The pair of supported portions are swingably supported by the corresponding supporting portions, respectively.
The case is configured to be swingable about a first axis which is parallel to the first direction and close to the one end edge, between a first position at which the case is inclined in a direction away from the reference surface and a second position at which the case is positioned close to the reference surface, by of the pair of supported portions being supported by the pair of supporting portions of the carriage.
Between the carriage and the case, a positioning portion is provided to position the case with respect to the carriage in the first direction. The positioning portion includes a projection and a recess. The projection is provided on a side of the one end edge of the carriage to project from the reference surface toward the case in a state that the case is at the second position. The projection has a flat upper surface at a height which is equal from the reference surface of the carriage with respect to the first direction and the second direction. The recess is provided in the case and the projection is fitted into the recess in the state that the case is at the second position. In the reading unit, this kind of positioning portion is used to position the image sensor with respect to the carriage in the first direction.